As a guitarist in Fiona Apple's band (he's performing with her on Tuesday, September 18, at Mesa Arts Center), Lucinda Williams, Cass McCombs, Billy Gibbons of ZZ Top, Katey Segal, Conor Oberst, Julian Casablancas, and more, Mills has turned heads with his guitar prowess. But he'll be opening Apple's shows on her upcoming tour as a solo act, as well, performing songs form his 2010 record, Break Mirrors.

The songs ought to earn him as much notice. The record is remarkable, balancing folksy balladry with hard-edged pop, acoustic guitar murmurings against electric guitar ravers. Mills' voice is strong and clear -- possessing an ease and confidence that shines on through the songs.

We spoke with Mills about songcraft, his influences, and Fleetwood Mac.

Up on the Sun: You've worked as a session musician, sideman, and producer. What influenced your decision to get on the other side of the process as a songwriter?Blake Mills: Writing songs has always just been something I've done. I started in the sort of professional music world playing in bands and writing, but I've always been moved by songs. Part of being a musician is just trying to pass that on; it's just part of the game. When you write a song and someone goes "Ah, I know that feeling. I've been there." [Songwriting is] driven by the same thing that inspires me to put a record on. When somebody nails something that you've gone through, you get this weird light that goes off in your head, like, "That's exactly what it is, and you put it into words." That's really the gist of it.

Break Mirrors came out in 2010, but the live performances vary greatly from the versions on the record.

All the performances of those songs have had lives of their own, intense and special. It depends on who's around. It depends on what we've been listening to, or who I'm opening for, who I'm playing with. It's fun; it feels a little like a puzzle. If you're going to tell a joke over and over again, you tell if different ways each time. You lead up the punch line differently, but the punch line always stays the same.

What kind of difference in headspace does writing your own songs require, versus playing someone else's tune?

When you're playing guitar for somebody else's tune, you're kind of reacting. You're reacting to things that they're giving you. When you're writing, you're processing, trying to understand things, thoughts, and feelings and process them into music and melodies. It's a bit of a different translation process. But they're both trying to interpret something. There are similarities, but for the most part it's a bit of a different thinking cap.